The Tofoo Company: Bean Screening Trial.
During the last PPMA show we were recommended by another exhibitor to the Tofoo Company as someone who would be able to help them with screening their product to remove any under soaked beans from their production line. The product was coming from a water flume through a dewatering belt and then into a tank prior to a secondary treatment. It was within this process that they needed to remove any under soaked beans which were smaller and harder than the beans they wanted to remain in production. The harder ‘stone’ beans represented around 8 to 10% of the beans that were processed.
The Tofoo Company were processing 7.5 tonnes of dry beans a day, which were soaked for 16 hours to generate 17 to 18 tonnes of soaked beans per day. The amount of stone beans they would need removing was around 700 kilos, which would not be reprocessed. 90% of these stone beans would need to be removed in order to protect the grinders, as even small quantities getting through will impact on the grinders and cause trips and loss in production.
As part of the design found a way of dealing with this issue by using a screening conveyor. To make sure that our equipment would screen the beans efficiently we conducted product trials at or factory. Here we received 2 bags of beans, 1 we had to soak for 12 hours and the other was an accurate representation of the stone beans for size. We carried out the trials using an 8mm diameter screen and we achieved good removal with limited damage, and an excellent extraction rate.
As the space they had for the screening conveyor was limited and we needed to add a dewatering option at the start. The next stage was to send the Tofoo Company a test screening conveyor, so they could add in into their production line. As part of this phase, we also needed to review the plan for a long-term solution, the design / build phase and the earliest installation date. Before we released the test conveyor we need to make sure that we could fit it into the tight space and that it could deal with the capacity as even if they were dealing with even only 5% stone beans then the screened material could be as high as 600 kilos per day.
Our projects team used the factory layouts and supplied a CAD drawing of how the machine would fit in with the current layout as well as considering
- The flume discharge height
- The bean storage prior to grinding
- The discharge height for the stone beans and how to handle them
- The power requirements
After all of these points had been considered and agreed, a date was organised for the test conveyor to be delivered and installed.
During the on-location trial, further issues were then recognised, which is why trials are so important.
- Beans were getting stuck vertically in the perforated screen
- The bounce rate of the beans meant they did not fall through the gaps
- The screen became heavily loaded 2 and 3 deep at times as it was not well distributed
All these issues could be rectified by creating a mono layer of product by adding a metering conveyor with a buffer hopper which could regulate the product flow.
Due to the current crop and the reduced amount of stone beans that they were currently experiencing, the current line could cope with the current levels without needing to screen. Which is a huge win for them. Future development discussions are still taking place on how we can integrate a screen into the operation instead of a dewatering conveyor for future crops.
The test screens delivered substantial stability during a period when they had high levels of stone beans.